Author meta fields aren't displaying correctly due to broken logic

Description

Some authors have missing meta data even though the data are in the database. For example, some authors' description/biography are empty when retrieving them from the_author_meta('description'), even though $authordata->description from the function shows the data correctly.

This is caused by a bug in wp-includes/author-template.php, starting from line 99:

To reproduce this, you must have a users table that still has user_description in the schema. user_description hasn't been in the users table since 2.0. Somehow the schema for the users table in question has not been updated for a long time.

For the case of user_description existing in meta, 3.3.1 already correctly handles mapping this to description.

Fix a notice in [20565] where get_the_author_meta() may be called prior to postdata from being set up. In this case, the function should return nothing (via the filter). props johnjamesjacoby. fixes #20529. see #20285.